(CBS/AP) Opposing lawyers in the John Edwards trial wrangled Friday over whether to allow as evidence a sex tape of the former presidential candidate and allegations of an extramarital affair involving an ex-aide who is the prosecution's chief witness.

Prosecutors objected when a defense lawyer for Edwards asked former aide and confidante Andrew Young whether he had threatened to release a "private video" to expose Edwards' affair with Rielle Hunter.

U.S. District Court Judge Catherine C. Eagles instructed Edwards lawyer Abbe Lowell to proceed with his cross-examination of Young without mentioning the tape, saying she would rule whether it was admissible later Friday.

Hunter sued Young in state court two years ago over ownership of the sex tape and other personal items in Young's possession. That civil suit was settled earlier this year with an agreement to destroy all copies of the tape, though there are suggestions in court documents that federal investigators may still have a copy.

Defense attorneys had no intention of showing the tape to the jury, but wanted to mention it in the context of the allegation that Young threatened Edwards.

Young was the first witness called by prosecutors after opening statements Monday and he has remained on the stand all week. His testimony is essential to making the government's case that Edwards directed a conspiracy to use nearly $1 million in secret payments from two political donors to help hide his pregnant mistress as he sought the White House in 2008. Edwards denies knowing about the money and has pleaded not guilty.

On the witness stand, Young has admitted much of the money at issue in the case was siphoned off to pay his family's personal expenses, including the construction of his $1.5 million home, and not to buy Hunter's silence.

Later, Lowell questioned Young about his contacting three witnesses in the case following the release of the defense's witness list. Despite having been instructed by prosecutors not to contact any other witnesses, Young admitted he called two men and a woman.

Without the jury present Monday, Judge Eagles told the defense it could mention Young had called the witnesses in opening statements, but barred Edwards' lawyers from characterizing the contact as "witness tampering" or mentioning that Young had previously had a "one-night stand" with one of the witnesses.

On Friday, Lowell asked Young what he had asked the woman when he called.

"It was for a personal issue, sir," Young replied.

Asked how the woman described her potential testimony, Young replied that she said she would tell the truth. That prompted Lowell to ask Young if he responded by telling her that the truth would "mess up everything."

Young said he may have said that, but couldn't recall.

Concerned about the direction of the testimony, Eagles dismissed the jury and broke for lunch early.

Both Young and the female staffer in question, who was named in court, are married. Young's wife, Cheri, is expected to be called to the witness stand after her husband completes his testimony.

Earlier this week, the prosecution also tried to plug potential holes in Young's testimony, focusing on inconsistencies such as why Young had written in his tell-all book, "The Politician," that the donations "were gifts, entirely proper, and not subject to campaign finance laws."

Young answered that, at the time, he wrote that the donations were legal for a simple reason: "I was scared to death," said Young. "I did this to cover my butt."

The prosecution's case hinges on whether the money -- nearly $1 million in donations from wealthy donors -- was used to simply hide a mistress or to help keep Edwards' campaign afloat.

Analyst Jan Baran says Young "has testified very much to the detriment of the Edwards defense in the sense that he's said there were a lot of conversations with people about this cover-up and how it was campaign-related."

But as Edwards' attorneys dig in with their attack on Young's credibility, Edwards himself seemed upbeat as he left the courthouse Wednesday afternoon with his daughter, remarking to her that the sun was out in more ways than one.

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